Volume 52, Nº 3 (2016)

The results of studies aimed at developing E30 bioethanol fuel composition using heavy low-octane hydrocracking gasoline as the basic component are reported. The dependencies of knock resistance, saturated vapor pressure, and fractional composition on bioethanol concentration in a mixture with heavy hydrocracking gasoline are shown. The maximally permissible concentrations of additional components (light hydrocracking gasoline, toluene, and reforming gasoline) in the fuel are indicated. The results of tests of experimental specimens in compliance with OAO VNII NP (OJSC All-Russian Scientific Research Institute of Oil Refining) technical specifications and calculation of economic feasibility of production and use of E30 bioethanol fuel are presented.

A versatile biodiesel production process that allows simulation of a plant that can produce biodiesel by transesterification of vegetable oils of any composition to methyl esters is proposed. The validity of the simulation was verified by producing biodiesel and glycerin from different amounts of algal oil feedstocks. The versatile model can be applied to different types of oils by changing only the input parameters. It provides a series of advantages not only in terms of resource and time saving when building a real plant, but also when selecting the most suitable feedstocks for biodiesel production.

The effect of gallium and its combination with zirconium on the acid and catalytic properties of pentasil in the upgrading of straight-run fractions in the absence of hydrogen was studied. Hydrogenation–dehydrogenation sites and medium–strength acid sites are formed upon the concurrent modification of phosphorus–containing N–Ultrasil by gallium and zirconium. An optimal ratio of these sites is achieved for Zr:Ga mass ratio 1:1 and this increases the rate of isomerization of nparaffins and the rate of aromatization of aliphatic and naphthenic hydrocarbons. Insertion of phosphorus into zeolite leads to an increased yield of liquid products due to weakening and redistribution of the acid sites.

The composition of the structural fragments of resinous and asphaltic molecules in Usinsk heavy oil containing C – S sulfide bonds and of organosulfur compounds in the oily components of this petroleum was studied. The composition of the sulfur–containing fragments of the asphaltenes was studied separately for their low– and high–molecularweight fractions and occluded maltenes. Alkanes, naphthenes, mono and polycyclic aromatic hydrocarbons, dibenzothiophenes, and monobasic aliphatic acids were found in the fragments of the resinous–asphaltic compounds linked by sulfide bridges. The sulfur–containing structures of the oily components are represented by alkyl–substituted thiophenes, benzo, dibenzo, and benzonaphthothiophenes, and bicyclic sulfides. Heat treatment of this petroleum leads to decomposition of the resins and asphaltenes at the sulfide bridges and transition of individual fragments in the distillates, which must be taken into account in upgrading procedures.

The process of synthesis of 1^st-, 2^nd- and 3^rd-generation dendritic polyamidoamines (PAMAM), using ammonia and ethylenediamine, is described. It is shown that the oil drops disintegration rate constant and the degree of breakdown of a stable oil–water emulsion increase with each subsequent generation of the dendrimer and with its increasing concentration. The maximally attained degree of separation of water containing 68 mg/L of oil was 84.6% with the addition of 20 mg/L of 3rd-generation PAMAM. The demulsification mechanism is shown to be associated with the spherical shape of the dendritic PAMAM macromolecules and the presence of a large number of polar amino functional groups on the surface of these spheres.

Correlations have been found between some physicochemical properties of diesel fractions and color coordinates in the sRGB color space profile, permitting the rapid determination of relative density, flash point, and initial boiling point of the diesel fractions from photoimages. The suitability of this method was shown by statisticalanalysis. This method can find application for prompt monitoring of the quality of diesel fractions during refinery operations.

In the process of oil field development by fire flooding, some sections of the tail gas gathering pipelines may get frozen and blocked due to high content in the gas of moisture, methane, ethane, carbon dioxide, and hydrogen sulfide. To solve this problem, investigations were conducted to determine the effect of tail gas components, flow rate, pipeline length, and surrounding temperature on the process of reduction of transmission capacity of the gas pipelines due to freezing and blocking. It was found that the methane content in the gas is mainly responsible for gas hydrate formation and wall freezing, which occur predominantly in the back parts of straight pipes and pipe elbows and junctions. According to calculations, 70% methanol concentration is the best hydrate inhibitor.

A mathematical model (numerical simulation) of gas-oil flow in a multi-cup downhole gas-oil separator is proposed. The model takes into account the Gibbs wave equation to obtain the pump plunger velocity and the population balance model (PBM) for describing bubble aggregation and breakage. The gas-oil flow field distribution and the bubble behavior in the multi-cup gas-oil separator were simulated using computational fluid dynamics (CFD). The numerical simulation results showed that the main role of gas-oil flow distribution in the process of oil separation from the separator cup wall is the viscous effect. Small bubbles in the center tube aggregate into large bubbles, and interaction of the bubbles along the flow and the fluid running down the cup wall forms a clockwise spiral, which accelerates separation of the gas and oil phases in the separator cup. During the upstroke, the oil volume being sucked out by the center tube through the small hole is larger than the oil volume in the separator cup, which causes entry of air into the center tube and failure of the separator cup.

A sequence of possible reactions occurring during evolution of deep-lying fluids, components of which could be sources of biogenous oil substances, is studied within the confines of biogenetic concept of formation of oil. Oxidative condensation transformation of methane and its immediate homologs under the action of sulfur present in some fluids might have facilitated formation of various types of hydrocarbons and organosulfur compounds. The possibility of such transformations is supported by the stable direct correlations between sulfur concentration in oils, their density, viscosity, content of asphaltic-resinous components and heavy fractions, and the scale of oil deposits. The proportion of gas in the oil-gas systems decreases with increase of sulfur content. Metals, like V and Ni, in the deep-lying fluids affect the geochemical type of oil. Vanadium oils are heavier (V > Ni), have high sulfur contents, and occur closer to the surface, while Ni oils are lighter (Ni < V), have low sulfur contents, and occur in deeper strata. These characteristics apparently stem from the different nature of catalytic properties of the metals and the structures containing them. Transformations of the oil fluid with the involvement of heterocomponents thus affect the fractional and chemical composition of oil-gas systems.

The results of determination of thermal stability of mineral and partly synthetic motor oils are presented. The criterion of thermal stability is substantiated and the correlation between it and antiwear properties of the oils is determined. Direct photometric measurement method, which helps obtain an integral parameter of accumulation of all degradation products in the studied oil that can be determined from the luminous flux absorption coefficient, is chosen as the basic method of evaluation of thermal degradation processes. The essential feature of the method consists in comprehensive evaluation of thermal stability and antiwear properties of lube oils from the parameters, namely, the coefficient of luminous flux absorption, relative viscosity, vaporizability, and wear. Correlations of optical properties, viscosity, vaporizability, and antiwear properties of the lube oils with thermostating temperature are obtained, and based on them the limiting temperature of lube oil performing ability was established.

The amount of heat radiated by flares is important for designing and locating flare systems. No methods are described in the literature for predicting radiation of enclosed ground flares. To investigate radiation of enclosed ground flares, a series of gas flares were simulated in this work by computational fluid dynamics (CFD). The radiation values derived by CFD simulation match the experimental data. For methane, propane, and butane flaring, the radiation flux of 15.77 kW/m² was attained only above the flare system, so radiation will not affect the integrity of the structures. The radiation flux at the ground level was below 1.58 kW/m², so this area is safe for personnel. For hydrogen, the radius of isopleth of radiation flux of 15.77 kW/m² can reach 33 m, so towers and elevated structures should not be located in these areas. The radius of isopleth of radiation flux of 6.31 kW/m² can reach 70 m, and on the ground the radius of isopleth of 1.58 kW/m² radiation flux can reach 120 m. Radiation decreases with increase in enclosed ground flare height, so the safe distance of enclosed ground flare can be reduced by increasing the ground flare height.